Jonathan Kehayias brings up some of the reasons he tends to recommend customers keep away from using readable secondaries on Availability Groups:
A lot of the implementation questions I get for Availability Groups are generally looking at leveraging a secondary replica for High Availability or Disaster Recovery and often times also for offloading reporting or readable workloads. Readable Secondary copies of the database are really simple at the surface conceptually, but there are a lot of additional considerations I make that could lead you to another technology entirely like Transactional Replication or Log Shipping with Standby. Let’s look at how these three stack up against each other for different data access requirements.
There are some good reasons here not to kick replication and log shipping to the curb.